2025-06-23_REVISION - M1980244 (23)

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Docusign Envelope ID:45B9721 C-FDE2-4821-B686-80BBC79CA6DD structural fill or bedrock. During operations, a haul road will be constructed from the southwest to the northeast portion of the pad, allowing for ore to be loaded on the VLF." • 11. Section 7.2 discusses the Power Supply and backup generators on-site in case of a power outage. It is understood that preventive measures have been taken in response to the March 2024 storm event to shore up the backup power supply systems. It is also understood that a more thorough and comprehensive revision will be submitted following the conclusion of the on-going Rule 7.4.3 Independent Reviewer Evaluation of the storm event and VLFs.At this time, please update Section 7.2 to provide information regarding the existing and now additional preventive measures, including maintenance and testing schedules, additional structures or any other mitigation measures that have been or will be put into effect to ensure the reliability of the backup power systems for the site. Section 7.2 has been updated. 12. Within Section 7.2, Paragraph 2, it is stated that a 12-hour drain down period was used in the design of the PSSA. In accordance with the calculations presented in TR127, please discuss why a 24-hour drain down is not utilized. A 24-hour power outage scenario was used in the design for the PSSA. Section 7.2 has been revised. Exhibit E—Reclamation Plan (Rule 6.4.5): 13. Within Section 2.2, Paragraph 2, it is stated that 3.4 million cubic yards of growth medium are available from the existing and future development areas for the completion of reclamation which requires an approximate 3.3 million cubic yards.Within Exhibit D, it is noted that all areas except a small portion of Joe Dandy Hill within the AM14 expansion areas is already disturbed.Table D-4: Growth Medium Storage Areas shows there is currently 2.8 million cubic yards are currently stockpiled. Please discuss this half a million • cubic yard discrepancy and provide evidence and thorough documentation that there is sufficient growth medium to accomplish the reclamation at the site. The apparent discrepancy between the 2.8 million cubic yards (CY) currently stockpiled and the 3.4 million CY referenced as available for reclamation is due to the difference in how material volumes are measured and reported. Specifically, the 2.8 million CY reported in Table D-4 of Exhibit D reflects compacted cubic yards (CCY), representing the volume of growth medium after being placed and compacted into stockpiles using large-scale mining equipment. In contrast, the volume referenced in Section 2.2, Paragraph 2 (3.4 million CY) is reported in loose cubic yards (LCY), which is the volume expected after the material is re-handled and spread for reclamation. As standard practice in earthmoving and mining operations, compacted materials swell when excavated or spread, increasing in volume. CC&V applied a conservative swell factor of 20%, resulting in an estimated 3.4 million LCY of growth medium available from the 2.8 million CCY stockpiled. This exceeds the estimated 3.3 million LCY required for reclamation activities. Notably, the 20% swell factor used in this calculation is conservative when compared to typical swell factors published in the Caterpillar Performance Handbook for similar materials (included with Attachment 3 Revised Exhibit E). This conservative estimate ensures that there is a sufficient margin to meet reclamation volume requirements even under less favorable assumptions. Therefore, based on standard conversion methodologies and conservative assumptions, the currently stockpiled growth medium is sufficient to meet the reclamation needs at the site. 14. Section 2.7.1, Surface Mine Backfill Areas, does not include information regarding the South Cresson mine area backfill approved in TR142. Please update this section accordingly and ensure Exhibit C and F maps reflect this revision. TR142 was submitted but not yet approved when Amendment 14 was originally submitted. Section • 2.7.1 has been updated to include information regarding the South Cresson mine area backfill as approved in TR142. SSR Mining Inc. PAGE 4/19 II'